feat(label): uses --ui-white for control-label css class in Dark and High contrast themes (#7505)

* feat(label): uses `--ui-white` for control-label css class in Dark and High contrast themes.

* feat(label): uses `apply` in control-label css class.

app/assets/css/bootstrap-override.css

@@ -12,8 +12,11 @@
 }
 
 .control-label {
-  color: var(--ui-gray-7);
-  font-weight: 500;
+  @apply inline-flex items-center;
+  @apply font-medium;
+  @apply text-gray-7;
+  @apply th-dark:text-gray-warm-3;
+  @apply th-highcontrast:text-white;
 }
 
 .vertical-center {
@@ -355,10 +358,6 @@ input:checked + .slider:before {
   color: var(--ui-error-9);
 }
 
-.control-label {
-  @apply inline-flex items-center;
-}
-
 .progress {
   height: 8px;
   border-radius: 4px;